Stories tagged natural disaster

Tomorrow – May 12 – marks the one-year anniversary of the devastating earthquake that tore open central China. I've come across two interesting articles regarding that anniversary. Disaster tourism – controversial to many – is huge in the area. And there's a mini baby-boom among couples who lost their only child in the rubble of the quake. Much clean up still needs to be done as this slideshow attests to. Click each link above to learn more.

Two volcanoes in Congo, Africa, are exhibiting signs of erupting soon. Here are the details. Half a million people live with in the impact zone of a major eruption. Lava flows from an eruption seven years ago from one of the volcanoes killed about 100 people.

Killer asteroid?: Artist conception of impact eventCourtesy NASAThe old “What really killed the dinosaurs” controversy is back in the news. And once again, it’s Princeton geophysicist Gerta Keller stirring up the pot.

Death from above?: Perhaps not.Courtesy Mark RyanKeller and her colleague Thierry Adatte of the University of Lausanne in Switzerland have published yet another paper challenging the prevailing theory that an asteroid was the major cause of the extinction of the dinosaurs at the end of the Cretaceous Period 65 million years ago. The extinction affected over 60 percent of animal species including all of the non-avian dinosaurs.

Actually a number of events were occurring around the end of the Cretaceous including long-term volcanic activity, rapid marine regression, and the infamous asteroid impact. There’s also evidence that some of the dinosaur population was already in decline 10 million years prior to the events. But the scenario is usually played out with the meteor coming late in the sequence and delivering the deathblow to an already weakened eco-system, and paving the way for mammals to take over the ecological gap.

K-T boundary layer: The Cretaceous-Tertiary boundary layer located near Trinidad, Colorado. The pale-gray 1-inch iridium layer (arrow) is sandwiched between coal layers and contains shocked quartz and other evidence of a large asteroid impact. The scale bar is 6 inches in length.Courtesy Mark RyanThe asteroid impact hypothesis was first proposed in 1980 by Luis Alvarez of the University of California after he and his son Walter discovered a claystone layer rich in the rare-earth element iridium and peppered with shocked quartz in many locations around the world. Iridium is a rare element not commonly found on the Earth’s surface but abundant in meteorites. Shocked quartz was first noticed in sand grains in craters created by nuclear test bombs and later in meteor impact sites. Alvarez hypothesized that the only other possible source for this naturally deposited strata would be from a large extraterrestrial object hitting the Earth. From studying the amount of iridium found in Cretaceous-Tertiary (K-T) boundary formations, he calculated that a bolide about 6 miles across would have been necessary to create that much iridium around the world. But at the time evidence of such an was unknown. It wasn’t until after Luis Alvarez’s death in 1988 that a crater on the Yucatan Peninsula near Chicxulub Mexico became the chief suspect. The Chicxulub impact crater was the right size and the right age fitting all the criteria of a Cretaceous extinction event.

But Keller claims the asteroid came too early to put the coup de grace on dinosaurs or any species for that matter. Her study of spherules in strata at localities in Mexico has convinced her that the asteroid collided with Earth 300,000 years before any mass extinction.

At El Penon, a location very near the impact crater site, Keller and Adatte studied a 30-ft layer of sandstone above the iridium layer that they calculated had been laid down at a rate of about 1-inch per thousand years. This means it took 300,000 years to pile up the entire section of sediment.

Fossils were analyzed on either side of the iridium layer and the researchers found that of 52 species counted below the iridium layer (meaning before the impact), the same 52 species were found above it, meaning the asteroid hadn’t caused any extinction. But at the top of the 30 feet of sandstone overlaying the iridium claystone things were different.

"The mass extinction level can be seen above this interval," Keller says. "Not a single species went extinct as a result of the Chicxulub impact."

The more likely culprit, according to Keller, is India’s Deccan Traps flood basalts which for several million years poured out tremendous amounts of lava and noxious fumes into the atmosphere that would have had put long and tremendous stress on the existing ecosystem. Keller seems to roll out a paper on the subject every year or so in the last decade. We covered some of her Deccan Traps research 2007 which you can read here.

Whatever the case we do know is that non-avian dinosaurs left the planet after the Cretaceous, as none of their fossils have been found above the K-T Boundary. Well, even that doesn’t appear to be the case anymore. Recent dinosaur fossils found in the San Juan Basin in northwestern New Mexico are suspected to come from a stratum that post-dates the Cretaceous extinction. More research needs to be done on the find, but even this wouldn’t be unexpected. Even after the host declares the party’s over, there are always some stragglers who just don’t want to leave.

In another reminder that "Tornado Season" has begun, a twister ripped through a small town in Arkansas last night, killing 3 people and injuring 2 dozen. Damage was also reported in several nearby communities, and more than 10,000 people were without power due to high winds. Like the storm chasers mentioned in Thor's post yesterday, I find tornados and severe weather fascinating, probably because it can be so dangerous and destructive. I think it's great that research has helped us to learn more about how these storms work, so we can better predict them and hopefully prevent deaths and injuries. Source: Reuters

That's not snow: Ashfall from Redoubt's ~6 am explosive event, April 4, 2009, as viewed from near Homer, AK. Photograph courtesy of Dennis Anderson.Courtesy Alaska Volcano ObservatoryAfter a week of a slightly lower activity level, Mt. Redoubt had another large eruption on Saturday, sending a plume of ash 50,000 feet into the sky.

Ash fall from volcanic eruptions is a major problem for folks who live in the areas impacted by these eruptions. I used to think of ash fall like snow. But its not snow - volcanic ash is tiny jagged pieces of rock and glass. Its hard (you can't use a snowblower to get rid of it, it'll wreck your blower), abrasive, mildly corrosive, conducts electricity when wet, and does not dissolve in water. Think about that - when it rains you don't get the ash washed away - you just get icky mud. Its a major problem.

Red River flooding: NASA image created by Jesse Allen, using EO-1 ALI data provided courtesy of the NASA EO-1 Team. Caption by Holli Riebeek.Courtesy NASA
This was the Earth Observatory Image of the Day today. It was captured by the Advanced Land Imager on the EO-1 satellite on March 28, 2009. The main channel of the river is slightly darker than the flooded land in these areas, an indication of how extensive the flooding is.

Mt. Redoubt's eruption in 1990: A dramatic, mushroom-shaped eruption column rises above Mt. Redoubt on April 21, 1990. Clouds of this shape, which are produced when the upper part of an eruption column attains neutral buoyancy and is spread out above the troposphere-stratosphere boundary, are common during powerful explosive eruptions.Courtesy USGSAlso be sure to check out the Alaska Volcano Observatory's page on Mt. Redoubt's activity.